Complexes of (bpy)2Ru(II) and (Ph2bpy)2Ru(II) with a series of thienophenanthroline ligands: synthesis, characterization, and electronic spectra

Abstract

A series of complexes (bpy)2LRu(II) and (Ph2bpy)2LRu(II), where bpy is 2,2′-bipyridine, Ph2bpy is 4,4′-diphenyl-2,2′-bipyridine and L is 1,10-phenanthroline (phen), [1]benzothieno[2,3-c][1,10]phenanthroline (btp), naphtho[1′,2′ : 5,4]thieno[2,3-c][1,10]phenanthroline [ntpl, l=linear], and naphtho[1′,2′ : 4,5]thieno[2,3-c][1,10]phenanthroline (ntph, h=helical) were synthesized and characterized using 2D COSY NMR spectra. The UV spectra were assigned to study their metal to ligand charge transfer (MLCT) excited states. Complexes of (bpy)2LRu(II) showed identical absorption wavelengths (λ max) for the MLCT of all four members of the series with the only variation being the intensity (log ε ) for each. The MLCT of (Ph2bpy)2LRu(II) showed the similar behavior only with different wavelengths showing that in this heteroleptic series of complexes the MLCT is exclusively to the bpy ligands with none to thienophenanthroline (btp, ntpl, or ntph).